Over the years there have been a number of proposals of positive displacement apparatus of the scroll type, frequently, but not always, for use as compressors in refrigeration systems. Such apparatus may also be utilized as expanders or in some instances as pumps. Though theoretically practical, scroll type apparatus has not been commercialized to any significant extent due to a variety of problems including sealing and wear.
As is well known, such apparatus include two scrolls with interfitting vanes. One scroll is made to orbit, but not rotate with respect to the other with the result that a traveling pocket between the vanes on the opposed scrolls is formed which moves from an inlet to an outlet. When the apparatus is used as a compressor, the configuration is such that the pocket becomes progressively smaller. Conversely, when used as an expander, the pocket becomes progressively larger. When used as a pump for incompressible fluids, the pocket will remain of constant size.
Generally speaking, such scroll apparatus have been of two types. In one type, one scroll is generally stationary while the other orbits with respect thereto. In another type, both scrolls rotate while in addition, the vanes on one of the scrolls orbit with respect to the vanes on the other. In some instances, combinations of both forms have been employed.
In any event, it is necessary that the vanes properly interfit and that there be proper movement and synchronism of one scroll relative to the other.
To achieve these goals, the prior art has generally resorted to highly precise component fabrication techniques and structure. For example, considerable pains are taken in forming the vanes on the scrolls so that they will properly interfit with each other during operation. In addition, numerous structures such as Oldham rings have been utilized to provide the desired synchronization. As a consequence, the expense of the units has been relatively high and the desired success has not yet been achieved because of high wear rates in the structure due to the high forces imposed in either type of system resulting from the fact that one scroll must move eccentrifically about an axis creating large bearing loads.
The present invention is directed to overcoming one or more of the above problems. Prior art of possible relevance with respect to the invention include the following U.S. Pat. Nos.: 3,874,827 issued Apr. 1, 1975 to Young and 4,371,323 issued Feb. 1, 1983 to Fischer et al.